Good guesses but I was quite staggered...http://s1073.photobucket.com/albums/...er_media_share
...due to traffic I was diverted (by Sat Nav) to come off the M6 at Stoke and go along A roads at a steady 50/60, same coming back, which must have helped. Started to drop once I reached motorway speeds.
(32.7 mpg in case the link doesn't work!)

Mate, if Id have thought I would have checked your whereabouts, sorry! Will be back so will check next time.

Obviously, this is just a fun thread, Im not suggesting we all dash out & buy a 370z for its commuting prowess (this reading is grossly misrepresentative!) but quite impressive nethertheless. I should point out I was expecting about 27mpg myself (had I not been diverted off the M6 I reckon it'd be nearer). Next time however, when the QQ is not available, guess which route Ill be taking!!